Dead end clamp



Q 1931 H. E. MCDOWELL ,825,

' DEAD END CLAMP Filed Oct. 1. 1930 /Q J; I

I] 525 'l l M Wm wow law A TTOk/VE Y Patented Oct. 6, 1931 PATENT OFFICE HAMILTON E. MCDOWELL, OF NEW YORK, N. Y.

DEAD END CLAMP Application filed Gctober 1, 1930. Serial No. 485,666;

This invention relates to clamps for hold: ing conductor wires such as the dead ends of transmission conductors and other cables and has for one of its objects the provision of a conductor clamp which will effectively hold the conductor without subjecting it to in ury.

Another object of the invention is to provide a conductor clamp of the class described which shall be simple and economical to man- W ufacture and which shall have a maximum holding capacity for the weight of the clamp.

Another object of the invention is to provide a clamp which can be used for cables of-different diameters.

Other objects and advantages will appear from the following description.

The invention is exemplified in the combination and arrangement of parts shown n the accompanying drawings and described in the following specification, and it is more particularly pointed out in the appended claim.

In the drawings:

Fig. 1 is an elevation of a clamp embodying the present invention.

Fig. 2 is a top plan of the clamp shown in Fig. 1. I

Fig. 3 is a section on line 3-3 of F g. 1.

Fig. 4 is a section on line H of Fig. 1.

In dead-ending a transmission line, the conductor may be gripped between clamping jaws with sufficient force to withstand the tension in the conductor, but this manner of securing the line is open to the objection that the conductor may be marred by the pressure of the clamping jaws decreasing the strength of the conductor and producing a tendency for the conductor to fail'under load. This method of securing the conductor also concentrates the load at one point instead of distributing it over an extended surface.

Another method of dead-ending the conductor is to wrap the conductor about a snubbing cylinder and clamp the slack end. Where the snubbing block has a uniform curvature, the taut end of the conductor where it first engages the block will be subjected to undue pressure against the block unless a cylinder of large diameter is used and if such a cylinder is used, the clamp will be unnecessarily large and heavy.

The present invention contemplates a clamp having a snubbing seat with a large radius, of curvature where the taut end of the clamp enters the seat and a less radius of curvature adjacent the slack end of the clamp. This permitsthe force of the load to be taken up-gradually by the snubbing seat so that the pressure of the cable against the seat is approximately uniform throughout the length ofthe seat and only a fraction of the-tension in the cable is transmitted to the holding clamp at the slack end; the remaining portion of the tension being taken up by the snubbing action of the curved seat about which the cable is wound.

In the drawings the numeral 10 designates generally a snubbing member having a seat 11 about which the conductor 12 is turned.

The seat 11 as shown in Fig. 4 has inclined sides 18 forming a V-shaped trough in which the cable rests. gradually increased from the point 14 where the cable 12 enters the seat to the point 15 where the snubbing action is discontinued and the cable held by a clamp. Theoretically, the most efficient results can be obtainedby continuously decreasing the radius of curvatureof the seat in such a way that the pressure against the seat will be uniform throughout the snubbing range.

As pointed out in the application of Arthur vO. Austin, Serial Number 339,304, filed February 12, 1929, uniform pressure may be secured by employing a logarithmic curve for the snubbing seat. I have-discovered, however, that practical results can be obtained by forming the seat of a series of arcs having different radii.

In the form of the invention illustrated in the drawings, I used two radii for determining the contour of the seat. The portion of the seat from the point 14 to the point 16 is formed on an arc struck about a point 17 and having a radius 18. This are is tangent to the cable 12 at the point where it enters the seat and is continuous with a second arc struck about the point 19 with a radius 20.

In the present embodiment, the second arc The curvature of the seat is is continued to form a semi-circle which ends at the point 15. This forms a snubbing seat having a large radius where the cable enters so that a portion of the load is absorbed by the friction of the seat without producing undue pressure at the point of greatest tension. After the tension in the cable has thus been reduced, the radius of the seat may be decreased in order that the decreased tension may continue to produce sufficient pressure against the seat to secure the effect of the frictional contact between the cable and the seat. The slack end of the cable beyond the point 15 is held by a keeper 21 which clamps the cable against the continuation of the seat beyond the point 15. The portion of the seat opposite the keeper 21 is provided with a dip 22 to insure a firm grip of the cable between the keeper and the seat, and the keeper is provided with a projection 23 corresponding to the dip 22.

It will be noted that the keeper is provided with contact surfaces 24 and 25 at opposite sides thereof having different radii of curvature in transverse section. This feature in combination with the V-groove in the snubbing portion of the seat makes it possible to use a single clamp for cables of different sizes. The V-groove also increases the frictional grip of the clamp upon the cable. The keeper 21 is pressed against the cable by U-bolts 26 having nuts 27 for forcing the keeper against the cable. The U-bolts extend through an opening 28 in the snubbing block within the contour of the curved seat. The snubbing block may be provided with cross braces 29 and 30 or any other desired form of bracing members.

A pair of spaced cars 31 are secured to the snubbing block and provided with perforations 32 for attaching the block to an insulator string or other suitable support. The pivotal center of the opening 32 will be in alignment with the axis of the taut end of the cable 12 when the clamp is in use. It will be understood that various changes in detail of construction will readily suggest themselves to those skilled in the art without departing from the spirit and scope of the invention, and I therefore do not wish to restrict the invention to details of construction except as defined by the appended claim.

I claim:

A clamp for conductors or the like comprising a snubbing block having a snubbing seat therein which is V-shaped in cross section and which increases in curvature from the point of entry of the taut end of the cable toward the slack end of the cable, said snubbing block having a clamping seat ad- 'acent the slack end of the cable, and a eeper for pressing the cable against the clamping seat, said clamping seat and keeper having a dip therein curved in the opposite 

